Background The Al-Andalus physical activity intervention study is a randomised control trial to investigate the effectiveness of a land- and water-based exercise intervention for reducing the overall impact of fibromyalgia (primary outcome), and for improving tenderness and pain-related measures, body composition, functional capacity, physical activity and sedentary behaviour, fatigue, sleep quality, health-related quality of life, and cognitive function (secondary outcomes) in women with fibromyalgia.

Methods One hundred eighty women with fibromyalgia (age range: 35-65 years) will be recruited from local associations of fibromyalgia patients in Andalucía (Southern Spain). Patients will be randomly assigned to a usual care (control) group (n=60), a water-based exercise intervention group (n=60) or a land-based exercise intervention group (n=60). Participants in the usual care group will receive general physical activity guidelines and participants allocated in the intervention groups will attend three non-consecutive training sessions (60 minutes each) per week during 24 weeks. Both exercise interventions will consist of aerobic, muscular strength and flexibility exercises.

Discussion The investigators study attempts to reduce the impact of fibromyalgia and improve patients' health status by implementing two types of exercise interventions. Results from this study will help to assess the efficacy of exercise interventions for the treatment of fibromyalgia. If the interventions would be effective, this study will provide low-cost and feasible alternatives for health professionals in the management of fibromyalgia. Results from the Al-Andalus physical activity intervention will help to better understand the potential of regular physical activity for improving the well-being of women with fibromyalgia.

Inclusion Criteria:

• Age: 35-65 years.
• Meeting the American College of Rheumatology criteria: widespread pain for more than 3 months, and pain with 4 kg/cm of pressure reported for 11 or more of 18 tender points.
• Not to have other severe somatic or psychiatric disorders, or other diseases that prevent physical loading (Answer "no" to all questions on the Physical Activity Readiness Questionnaire-PAR-Q ).
• Not to be engaged in regular physical activity >20 minutes on >3 days/week.
• Planning to stay in the same Association during the study.
• Able to ambulate, with or without assistance.
• Able to communicate.
• Informed consent: Must be capable and willing to provide consent.

Exclusion Criteria:

• Acute or terminal illness.
• Myocardial infarction in the past 3 months.
• Not capable to ambulate.
• Unstable cardiovascular disease or other medical condition.
• Upper or lower extremity fracture in the past 3 months.
• Severe dementia (MMSE<10).
• Unwillingness to either complete the study requirements or to be randomised into control or training group.
• Presence of neuromuscular disease or drugs affecting neuromuscular function.